含SPH - II的含尘气体。隐式时间步进和天体物理阻力区
Dusty gas with SPH - II. Implicit timestepping and astrophysical drag regimes
摘要：
在一篇配套论文（Laibe & Price 2011 b）中，我们提出了一种在光滑粒子流体动力学（SPH）中模拟双流体气体和尘埃混合物的算法。在本文中，我们开发了一种隐式时间步长方法，该方法保留了SPH算法中线性和角动量的精确守恒，但与以前的方案不同，允许迭代收敛到任意精度，并适合于处理非线性阻力状态。论文I中提出的算法也扩展到处理现实的天体物理阻力制度，包括线性和非线性爱泼斯坦和斯托克斯阻力。该计划是基准测试套件中提出的文件I，包括i）dustybox问题的解析解和ii）解决方案的dustywave，dustyshock，dustysedov和dustydisc得到明确的时间步长。当时间步长与阻力停止时间之比r为1 < r < 1000时，隐式方法比显式时间积分快1- 10倍。
英文摘要：
In a companion paper (Laibe & Price 2011b), we have presented an algorithm for simulating two-fluid gas and dust mixtures in Smoothed Particle Hydrodynamics (SPH). In this paper, we develop an implicit timestepping method that preserves the exact conservation of the both linear and angular momentum in the underlying SPH algorithm, but unlike previous schemes, allows the iterations to converge to arbitrary accuracy and is suited to the treatment of non- linear drag regimes. The algorithm presented in Paper I is also extended to deal with realistic astrophysical drag regimes, including both linear and non-linear Epstein and Stokes drag. The scheme is benchmarked against the test suite presented in Paper I, including i) the analytic solutions of the dustybox problem and ii) solutions of the dustywave, dustyshock, dustysedov and dustydisc obtained with explicit timestepping. We find that the implicit method is 1- 10 times faster than the explicit temporal integration when the ratio r between the the timestep and the drag stopping time is 1 < r < 1000.
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